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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October from 12 to 15, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Remarks:
although the log Pow value is out of the testing method applicability domain, the results can be considered as suitable and well representative for the substance under investigation
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Version / remarks:
adopted July 27, 1995
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
photometric method
Type:
log Pow
Partition coefficient:
-2.1
Temp.:
20 °C
pH:
ca. 4
Type:
Pow
Partition coefficient:
0.008
Temp.:
20 °C
pH:
ca. 4

Calculated partition coefficient (Pow) and log Pow

Ratio of solvents (n-octanol : Water) Partition coefficient Log Partition coefficient pH conditions
Pow Mean Log Pow Mean Mean
10 : 1 0.0062 0.0065 -2.21 -2.19 4.02
0.0074 -2.13
0.0059 -2.23
5 : 1 0.0114 0.0114 -1.94 -1.94 3.96
0.0111 -1.95
0.0116 -1.94
20 : 1 0.0063 0.0063 -2.2 -2.2 4.21
0.0066 -2.18
0.0059 -2.23

Mean all ±95 % confidence interval

0.0081 ± 0.0020 - -2.11 - -

Measured concentrations

Ratio of solvents (n-octanol : Water) Measured concentration in n-octanol phase (µg/ml) Measured concentration in aqueous phase (µg/ml) pH
10 : 1 0.55 87.8 4.02
0.69 93.1
0.53 89.5
Mean  0.59 90.1
RSD % 15 3 -
Measured quantity of test item (Mo; Mw 25.6 µg 396 µg -
Total nominal quantity of test item (Ms) 416 µg
Total quantity of test item (Mo+Mw) in the two-phase system 422 µg
Recovery  101 %
5 : 1 0.57 49.6 3.96
0.52 46.6
0.58 49.7
Mean  0.55 48.7
RSD % 6 4 -
Measured quantity of test item (Mo; Mw 22.2 µg 389 µg -
Total nominal quantity of test item (Ms) 416 µg
Total quantity of test item (Mo+Mw) in the two-phase system 411 µg
Recovery  99 %
20 : 1 1.11 174 4.21
1.15 175
1.06 179
Mean  1.11 176
RSD % 4 2 -
Measured quantity of test item (Mo; Mw 50.5 µg 405 µg -
Total nominal quantity of test item (Ms) 416 µg
Total quantity of test item (Mo+Mw) in the two-phase system 456 µg
Recovery  109 %
Conclusions:
log Pow: -2.1 at 20 °C and pH ca 4
Executive summary:

The partition coefficient of the test item was determined using shake-flask method, in accordante with the method and procedures outlined into the OECD guideline 107. The concentration in the aqueous and octanol phases was determined by spectophotometric validate method. On the basis of the preliminary assay, the value of the partition coefficient was estimated to be 0.0004, which corresponds to log Pow of -3.4.

Three experiments were carried out applying different solvent ratios. In the first experiment, the calculated volume ratio was applied, in the second, this ratio is divided by two and in the third, this ratio is multiplied by two. Test temperature was 20 ± 1 °C. Three parallel tests were carried out.

The partition coefficient (Pow) in n-octanol - water was determined to be 0.0081 ± 0.0020 (95 % confidence interval) at 20 °C and pH ~4, which corresponds to log Pow of -2.1 using the shake flask method.

Conclusion

log Pow: -2.1 at 20 °C and pH ca 4

Description of key information

log Pow: -2.1 at 20 °C and pH ca 4

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.1
at the temperature of:
20 °C

Additional information

OECD 107 - Shake-flask method